MO On the Employment of Platina 
tains and rivers along with the gold in small laminae, or 
it is obtained by washing the earth. When the largest 
grains of gold have been picked from the mixed 
mass of gold and platina, the remaining gold is ex- 
tracted by amalgamation; by means of which operation 
the platina is left behind in the form of flat plates or 
scales. 
The deceptions formerly practised by mixing gold 
with platina have induced the Spanish government to 
prevent the exportation of it, and to give orders to all 
their servants in that country to keep the platina by 
them, and to wash it in water from time to time. But 
as means have been found to detect easily and in a cer- 
tain manner the adulteration of gold with platina, and 
also to employ it for valuable purposes, it is to be 
hoped that the Spanish government will not persist 
in causing a prohibition so injurious to the arts and 
to its own finances to be executed with the former se- 
verity. 
My object at present is not to enlarge on the chemi- 
cal and physical properties of platina, but only to of- 
fer a few observations on the uses in the arts to which 
it has hitherto been applied ; and then to give an account 
of the result of an experiment which I made in regard 
to a new application of this metal to objects of manufac- 
ture. 
The apparent infusibility of platina by itself, formerly 
considered as an insuperable obstacle, was sufficient to 
prevent the employment of it except in combination 
with other metals, as experience showed that it was ca- 
pable of uniting with the greater part of them by fusion. 
Of such mixtures, that arising from a combination of 
brass and platina was found to be exceedingly proper 
for the specula of reflecting telescopes, as this alloy was 
* Platina is found in Spain, and also in St. Domingo. 
